1. Field of the Invention
This invention relates to a magnetoinductive flowmeter incorporating an electromagnetic circuit with at least one coil and a minimum of two detachably interconnected components of a magnetic material. This type of magnetoinductive flowmeter has been described earlier, for instance in DE 34 20 963 C2.
2. Background Information
The general technical concept of a magnetoinductive flowmeter has been well documented in prior art, for example in K. W. Bonfig, “Technische Durchflussmessung” (techno-industrial flow measurement), 3rd edition, Vulkan-Verlag, Essen, 2002, pp. 123-167. The fundamental concept of a magnetoinductive flowmeter goes all the way back to Faraday who in 1832 proposed employing the principle of electrodynamic induction for flow-rate measurements. According to Faraday's law of induction, a flowing medium that contains charge carriers and travels through a magnetic field will generate an electric field intensity in a direction perpendicular to the direction of flow and to the magnetic field. A magnetoinductive flowmeter utilizes Faraday's law of induction in that a magnetic field device typically comprising two coils generates a magnetic field and directs it through the cross-sectional lumen of the measuring duct, said magnetic field including a magnetic-field component that extends in a direction perpendicular to the direction of flow. Within this magnetic field, each volume element of the medium flowing through the magnetic field and containing a certain number of charge carriers contributes the field intensity generated in the volume element, to a measuring voltage that can be collected via the electrodes. A salient feature of magnetoinductive flowmeters is the proportionality between the measured voltage and the flow velocity of the medium, averaged across the diameter of the measuring duct, i.e. between the measured voltage and the volume of flux.
Magnetoinductive flowmeters are often of a modular design, consisting of multiple components such as coils, inductor cores, pole shoes, feedback plates etc. In many cases, these components must be produced to stringent precision specifications to ensure a precise fit and correct mutual alignment of the components when the magnetoinductive flowmeter is assembled. One requirement, among others, is the generation of a predefined magnetic field with highly specific properties.